【作者】 程波；

【导师】 万继光；

【作者基本信息】 华中科技大学 ， 计算机系统结构， 2011， 硕士

【摘要】 在过去的几十年中,并行I/O系统被广泛应用于科研和商业领域。大规模存储系统在提供海量存储空间和高速访问速度的同时也带来了大量的能耗,增加了数据中心的成本。大多数已有的节能技术通过在合适的条件下关闭一部分磁盘来降低能耗,但没有考虑这种方式对系统的可靠性和性能的影响。通过对现有节能技术研究,在级别为10的冗余磁盘阵列的基础上提出了一种使用小容量冗余磁盘阵列作为写缓存的节能阵列。系统将镜像磁盘阵列中的每个主盘保留一部分存储空间组成一个小的磁盘阵列作为写缓存,而将镜像磁盘全部设置成低能耗状态以达到节能的目的。为了提高写请求的处理速度,写缓存采用日志写的方式。在镜像盘处于低能耗状态时,以冗余阵列的方式组织缓存能够保证系统的可靠性。从主盘中保留出来的空间很小,不会降低数据的存储空间。节能阵列在企业级iSCSI目标器的底层增加一个节能模块,使用Linux内核态磁盘阵列软件来组织磁盘数据。节能模块主要包括请求处理,磁盘控制和倒盘三个模块。请求处理模块负责接收上层数据,判断数据存储的位置然后将数据发往合适的位置。磁盘控制模块根据条件转换磁盘状态;倒盘模块在缓存空间达到阈值时将缓存中的数据写入的数据盘和镜像中盘。通过基准测试工具和trace驱动的负载测试,验证了节能整列在写负载比较集中时能耗比Linux内的磁盘阵列软件要小50%,而性能与之相当。通过理论分析和测试可以看出,实现的节能阵列在写请求比较多的环境中节能效果明显。更多还原

【Abstract】 In the last decades, parallel I/O systems are widely used in scientific and commercial fields. Large scale storage systems have increased total cost of data center while providing great storage capacity and performance. Most of the energy conservation technology tend to turn part of disks into low power state to reduce energy consumption, but didn’t deal with the reliability and performance decrease.After investigating several energy conservation technologies,an new architecture that using sub-RAID as write buffer based on RAID10 is designed. Space that deserved from primary disks of RAID10 is organized as RAID5 which is used as a write buffer, while mirror disks are turned into low power state to conserve energy. In order to improve write performance, write requests are written to write buffer sequentially. When the mirror disks are in low power state, the system is still reliable because the write buffer is organized as a RAID5. As only little space is deserved from the primary disks, the storage space will not decrease much.An Energy conservation module is added in the bottom of IET to form an energy-efficient RAID. This module contains three smaller modules: request hander, disk controller and destager. Request hander is responsible to receive data from upper layer, and decides the position of data and redirects it to the right position. Disk controller is used to change disk states according to several conditions. Destager is activated when the space of write buffer is lower than threshold, and update data to primary disks and mirror disks.We evaluated our energy-efficient RAID by running some benchmarks and trace driven loads. The result show that our energy-efficient RAID can reduce 50% power cost than MD while keeping the same write performance. By test results and analysis, our energy-efficient RAID can reduce power cost obviously when the write requests are intensive.更多还原